Lubricating oil composition, inhibitor therefor, and method of manufacturing the same



Patented Aug. 19, 1941 LUBRIGATING OIL COMPOSITION, INHIB- ITOR THEREFOR, AND METHOD OF MAN- UFACTURING THE SAME Troy Lee Cantrell and James Otho Turner, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.

12 Claims.

Our invention relates to lubricating oils and more particularly to lubricating oil compositions containing an oil-soluble agent or agents effective to inhibit or mitigate the normal corrosive or destructive action of lubricating oil deterioration products upon certain types of bearing metals under certain conditions of use, said agent or agents also having the properties of imparting so-called extreme pressure characteristics to the lubricating oil compositions, and also being effective to reduce or eliminate undesirable oxidation changes in the oil.

Despite the many technological advances made in the art of refining and applying lubricating oils and in the composition of bearing materials, modern lubricating oils and bearings often fail to perform satisfactorily. It is well known in the art that straight petroleum lubricants have fairly well defined limits of bearing speeds, pressures, and temperatures within which they will give acceptable service. These limitations are often exceeded in modern designs, resulting in machines that cannot be satisfactorily lubricated by straight mineral oils. These modern designs are justified by engineers in their efforts to provide machines to conform to the ever-increasing demand for compactness, speed, power, and acceleration in modern engines. Many modern designs have already exceeded the above-mentioned limits wherein straight petroleum lubricating oils perform acceptably; therefore, it is necessary to provide lubricating compositions that extend and widen the limits formerly associated with straight lubricating oils.

Moreover, highly parafiinic oils having excel- 1 lent viscosity-gravity constants, volatilities, carbon residue values, and resistance to sludging and oxidation, and hence of high value for use under relatively mild lubricating conditions, sometimes tend to be even less satisfactory than the less highly paraflinic oils, when the ordinary limits of temperature, pressure, and bearing speed are exceeded. This may be due in part to the fact that the deterioration products of paraflinic constituents are more active than those resulting from naphthenic or other nonparaflinic constituents, and it may be due also to the fact that the nonparaflinic constituents have some inhibiting effect upon either the deterioration of the paraflinic constituents or upon the behavior of products resulting from such deterioration, at high temperatures and pressures and in the presence of certain metals. However, the inhibiting value of the nonparaffinic constituents is low per unit concentration, and they are less satisfactory with respect to viscositygravity constant, carbon residue, and similar criteria of lubricating quality than the parafflnic constituents. A more satisfactory solution of the problem would be to substitute for the Application September 5, 1936, Serial No. 99,662

nonparaflinic constituents removed in the more drastic refining treatments or absent because of the-highly paraffinic nature of the original stock, some inhibiting or mitigating agent which would be far more effective per unit concentration and hence less detrimental with respect to the other physical properties which also affect the ultimate lubricating value of the oil.

Improved bearing'metals have recently been developed which are mechanically advantageous under many operating conditions. These bearing metals include binary and ternary alloys of cadmium, silver, copper, lead, and nickel; as examples of such improved bearing metals frequently employed at the present time we may mention cadmium-silver, cadmium-silver-copper, cadmium-nickel-copper, and copper-lead alloys. However, such alloys are more subject to chemical attack than babbitt and other hearing alloys used in the past, and their use at high temperatures, high speeds, and high pressures is sometimes accompanied by a deterioration of the oils employed for their lubrication, which in turn may destroy the bearings. The exact mechanism of this action is no doubt complicated and is perhaps not fully understood; it is quite possible that some of the metals present in the bearings tend to promote such deterioration, and that other metals present are subject to attack from the deterioration products. Whatever the cause or the mechanism, the result is that the combination of'drastic lubricating conditions and alloy bearings of the general nature indicated frequently causes troublep the bearings may be badly etched or corroded, and the quality of the oil may be rapidly deteriorated.

It has been observed in some cases that the more highly parafiinic oils are apt to cause more difficulty in this respect than less parafiinic oils. It is highly desirable, therefore, to provide means whereby the oils may be So improved as to give satisfactory operating results under the conditions noted, and this is especially true insofar as concerns the more highly'paraflinic oils, which should and do command a premium in price.

Moreover, it is well known that all hydrocarbon oils are more or less subject to changes through oxidation resulting in undesirable deterioration, acid formation, and increase in carbon residue, viscosity, sludging, and the like. Such oxidative changes may become more rapid or more far-reaching in extent in the presence of metals such as those employed in modern bearings, for example those of the general class mentioned above.

In order to meet these problems and to provide more satisfactory lubrication under the conditions indicated, various improvement agents have been incorporated in hydrocarbon oils prior to their sale and use. Some of these are extremely effective but too expensive for general use. Others, while having satisfactory inhibiting'or mitigating characteristics, are unsatisfactory for other reasons. A primary requisite of any such improvement agent is good oil-solubility under service and marketing conditions; moreover, since solubilities vary in different types of oils, the improvement agent should be capable of being added in the requisite amount to oils of different characters.

The improvement agent should also be highly eiiiective per unit concentration in the lubricating oil compositions; otherwise it would be necessary to add such an amount of the improvement agent as to substantially modify many of the desirable physical properties of the lubricating oil itself. The lubricating oils in which the improvement agents are incorporated have been carefully refined to meet exacting specifications, and if it is necessary to incorporate therein a relatively large amount of some agent difiering in physical properties from the oil itself, the resulting composition may prove unsatisfactory for the very purposes for which the lubricating oil was prepared. In general, it is desirable that the improvement agent should be effective at concentrations not exceeding one or two per cent by weight of the lubricating oil, although, as will be shown hereinafter, somewhat higher concentrations may occasionally b justified for special purposes.

Among the more available comparatively inexpensive improvement agents which have been suggested and employed for this general purpose are various oil-soluble compounds of phosphorus,

and especially trivalent phosphorus, for example aryl esters of phosphorous acid. Perhaps the specific agent which has been most largely used up tothe present time is triphenyl phosphite. This compound is sufliciently inexpensive to make its use economic in certain instances, but it does not represent an entirely satisfactory solution of the problem, and, for certain oils at least and under certain conditions, its use is definitely unsatisfactory. Triphenyl phosphite, while having moderate lubricating properties, is much less viscous and oleaginous than the lubricating oils in which it is usually desired to incorporate an improvement agent, for example extreme-pressure lubricants and automotive lubricants. Moreover, its solubility in hydrocarbon oils is not extremely good and this is particularly the case insofar as concerns the more highly refined or more highly parafilnic lubricating oils; in many cases, as little as 0.1% of triphenyl phosphite produces a definite haze or cloudiness immediately upon addition to hydrocarbon oils, and after remaining in the oil for a moderately extended period of time it may produce a definite sludging action, an action which becomes especially marked upon exposure to air or to sunlight or when the oil is packaged in metallic containers, such as cans made of tin plate, terne plate, and the like.

The inhibiting and mitigating properties of triphenyl phosphite with respect to corrosion of bearing metals of the class mentioned hereinbefore in many instances may be entirely satisfactory in themselves. But it will be obvious that if the oil has been deprived of the improvement agent prior to use, through sludging or precipitation, the eventual users of the oil may be deprlved of this potential benefit. In addition to its poor solubility and tendency to sludge, triphenyl phosphite, when added'to hydrocarbon oils which are subsequently packaged in metallic containers made of tin plate, terne plate or the like, tends to form deposits upon the surfaces of the metallic containers. Here again the problem happens to be more acute with respect to the more highly parafflnic oils, for the reason that such premium oils are generally and advantageously dispensed in sealed metallic containers rather than in-bulk, and because any clouding, sludging, or depositing action is more detrimental with respect to the sale of these highly refined oils, of which an important advantage from the sales standpoint is their improved appearance and attractiveness to the eye.

The simpler aryl and alkyl phosphites and phosphates, such as triphenyl phosphite and tricresyl phosphate, contain phosphorus in relatively high concentration, which fact tends in general to reduce the solubility of these compounds in hydrocarbon mixtures, especially in highly parailinic oils. It is also probable that this relatively high phosphorus content is responsible for their tendency to deposit out on metal surfaces at low temperatures.

Such phosphites leaving much to be desired in respect to anti-oxidant properties; the aryl phosphates may even have no antioxidant effect at all. The simple aryl phosphites, in particular, tend to hydrolyze in the presence of moisture, and .may, as a result of this action, exert a pronounced corrosive effect upon iron; it will be obvious that such hydrolysis will tend to form highly corrosive aryl acids, such as phenol.

It is therefore an object of our invention to provide an improvement agent or inhibitor having a satisfactorily high degree of solubility in hydrocarbon oil's, even the mor highly refined or more highly paraihnic oils, having a satisfactory inhibiting or mitigating effect upon the destructive action of lubricating oils upon alloy bearing surfaces under actual conditions of use where such destructive action would otherwise take place, and which, when added to hydrocarbon oils, will not result in sludging or in forming deposits at ordinary temperatures upon metallic packaging materials such as terne plate, tin plate, and the like, or other common metal surfaces.

It is also an object of our invention to provide an improvement agent or agents of the character indicated herein, having the property of imparting desirable extreme-pressure characteristics to hydrocarbon oils when incorporated therein.

Another object of our invention comprises the provision of an improvement agent or agents for addition to hydrocarbon oils, having desirable anti-oxidant and-stabilizing properties, and effective to retard increase in viscosity, carbon residue, acidity, and sludging of both highly parafiinic and less highly paraflinic oils.

A further object of our invention is to provide improved lubricating compositions comprising hydrocarbon lubricating oils and certain improvement agents incorporated therein.

A still further object of our invention is to provide a method or methods of manufacturing improvement agents having desirable characteristics for addition to mineral oils.

Our invention has for further objects such additional operative advantages and improvements as may hereinafter be found to obtain.

We have found that advantageous improvement agents or inhibitors of the character indicated can be prepared by reacting phosphorus trichloride (PCla) with certain anti-oxidants; said anti-oxidants comprising the water-insoluble reaction products obtained by reacting phenols with oleiines in the presence of sulfuric acid (H2804). Such anti-oxidants and methods of preparing the same are disclosed in the prior co-pending application of Stevens and Gruse, Serial No. 702,258, filed December 13, 1933, now issued as Patent No. 2,061,111, of November'l'l, 1936, and in the co-pending applications of Troy L. Cantrell, Serial No. 64,413, filed February 17, 1936, now issued as Patent No. 2,149,759, of March '7, 1939, and Serial No. 99,488 filed September 4, 1936, to which reference may be had for further details. The disclosures of the copending applications referred to constitute in effect a part of the disclosure of our present application, insofar as relates to the preparation of such anti-oxidant materials, which are used as a starting material in preparing phosphorus containing improvement agents in accordance with our present invention.

Referring, for example, to the aforesaid copending application Serial No. 99,488, there is disclosed a process of manufacturing antioxidants wherein a phenol is mixed with from one to ten per cent of sulfuric acid having a strength of sixty to one hundred per cent, or

even fuming sulfuric acids, and an olefine or a mixture of olefines is passed, preferably in the vapor-ous or gaseous phase, through the liquid mixture until the phenol undergoing reaction has gained in weight from 100 to 200 per cent, or

thereabouts, followed by washing the product so obtained with water and with caustic soda solution, the concentration of which does not exceed per cent. Variousphenols may be employed, for example phenol (CsHsOH) itself, the three cresols (C6H4-OHCH3), certain xylenols (C6Ha(CHa)z--OH), and crude cresylic acids also may be employed.- Where, in accordance with our present invention, the anti-oxidant thus prepared is subsequently to be reacted with PO13, the phenolic starting material should be as free as possible from pyridine bases; the presence of pyridine bases in the anti-oxidantproduct would result in undesirable reactions upon the subse quent treatment of the anti-oxidant with phosphorus trichloride. As olefinic material there may be employed individual olefines themselves, mixtures of oleflnes, or mixtures of olefinic and non-olefinic material. By way of example, the olefinic starting material may be butylenes, amylenes, refinery gases containing normally gaseous olefins (ethylene, propylene, butylene) in varying amounts, and cracked distillates or other relatively low-boiling hydrocarbon mixtures containing normally liquid olefins and in some instances also containing substantial amounts of dissolved normally gaseous olefins.

When the reaction is conducted with the olefin in the gaseous phase, the product is relatively highly concentrated with respect to effective anti-oxidant material and may not require distillation or concentration for the purpose of isolating the latter. On the other hand, when the reaction is conducted with the olefinic material in liquid phase, and especially when the concentration of olefins in the starting material is comparatively low, the product may be relatively dilute with respect to the effective anti-oxidant material, comprising for example a solution of such anti-oxidant in gasoline-like polymers or unreacted liquid hydrocarbons; In such case, the anti-oxidant material may be concentrated by distillation or otherwise as set forthin the abovementioned co-pending applications, prior to use in the process described herein.

The exact chemical and structural nature of s 01 possible chemical compounds is large and varied. In general, they differ from the simple alkylated phenols in that they are insoluble in dilute caustic soda solution, and also in that they are good anti oxidants and gum-inhibitors, whereas simple alkylated phenols are not. In general, also, the alkylations, in such instances as they occur, are of secondary and tertiary types; the methods set forth in the above copending applications do not produce normal or primary alkylation linkages. Alkylated phenols with normal or primary linkages are undesirable, due to the fact that both such materials and their products of reaction with phosphorus trichloride tend to be relatively insoluble in high-gravity lubricating oils. (It may be noted that insofar as the general problem set forth hereinabove is concerned, the high-gravity oils are the prin-:

cipal. offenders. Coastal and other low-gravity oils do not ordinarily require the addition of inhibitors, although their other lubricating properties may be and generally are less satisfactory than those of Pennsylvania and other highgravity oils.) It is possible that certain alkylated phenols of normal or primary linkage might be satisfactory provided the chains were long enough, say chains of four carbon atoms or more, on account of the closer resemblance in structure of such compounds to paraffinic lubricating oil constituents. However, this is doubtful and such compounds would be expected to be of prohibitive cost.

We have identified as constituents in the various anti-oxidant materials prepared as set forth hereinbefore such compounds as follow:

Ortho-isopropyl phenol Ortho-tertiary butyl phenol 2,4-ditertiary butyl phenol Ortho-isoamyl phenol Ortho-tertiary amyl phenol In addition to the above-listed compounds, similar derivatives of various homologues of mono-, di-, and polyhydroxy phenols may be present. It may be remarked, however, that while some of the constituents of such anti-oxidants may be identified, it is difiicult or impossible to identify all of the constituents of any one anti-oxidant material of the character indicated and it is equally impossible to say which particular compound or type of compound may be the most'important. As a. matter of fact, we have not been able to isolate or identify any single constituent or to recover any fraction of the concentrated anti-oxidants prepared in accordance with the aforesaid Cantrell application, Serial No. 99,488, which constituent or fraction has an antioxidant value as high as that of the total concentrated product. Nor for the purpose of our present invention is it necessary so to do; the fact remains that anti-oxidants may be prepared in the manner set forth hereinbefore and in the aforesaid co-pending applications, and such'materials comprise suitable starting materials for the manufacture of phosphorus-containing improvement agents or inhibitors in accordance with our present invention; certain of the constituents of the anti-oxidant startingmaterial which are not in themselves effective as antioxidants are nevertheless capable of being converted by reaction with phosphorus trichloride to phosphorus-containing materials useful as inhibitors.

As aforesaid, we prepare our improved addition agents or inhibitors by reacting anti-oxidants of the general character described hereinabove with phosphorus trichloride. The reaction is conducted by mixing phosphorus trichloride with the anti-oxidant material, in the desired amount, and heating the mixture until the latter is substantially free from chlorine and/or chlorides. In general, we prefer to regulate the amount of phosphorus trichloride added so as to secure a product containing-from one per cent or less to about five per cent of phosphorus; if the phosphorus content substantially exceeds five per cent, the resultant product tends to be insuificiently soluble in lubricating oils, especially highly parafiinic oils. It is one of the purposes of our invention, moreover, to provide oil-soluble phosphorus compounds of which the phosphorus content is lower than is the case with respect to simple esters of phosphorus acids, such as triphenyl phosphite and the like.

The amount of phosphorus trichloride added will of course vary with the character of the anti-oxidant material employed as the starting material. The safest rule, as stated hereinabove, is to regulate the amount in accordance with the percentage of phosphorus desired in the final product. It is, in general, desirable to so limit the amount of phosphorus trichloride added as not to efiect completion of reaction with all of the anti-oxidant used; the resultant product will then have a suitable inhibiting value, while still retaining some of the anti-oxidant value of the original starting material.

Before being brought into contact with the phosphorus trichloride, the anti-oxidant material should be dried to remove any substantial amount of. moisture contained therein. Conventional drying means may be employed. The dry antioxidant is then brought to a slightly elevated temperature, for example 80 F., and phosphorus trichloride is slowly added, the mixture being vigorously agitated by means during the addition. The amount of phosphorus trichloride added will in general vary from 5 to 30 per cent by weight of the antioxidant, and this amount may be added in two or more equal batches over a period of, say, two hours. During the addition period, there is a copious evolution of dry HCl gas; for this reason it is advisable to add the phosphorus trichloride well below the surface of the antioxidant liquid in .order to prevent the phosphorus trichloride from being swept out by the evolved gas and lost. After the desired amount of phosphorus trichloride has been added, the temperature is slowly raised to around 350 to 380 F.; the mixture is then maintained at this temperature until there is no further evidence of hydrogen chloride evolution, and HCl content of the product by analysis is less than 0.1 per cent. The resultant product, after cooling, represents the finished improvement agent or inhibitor of our invention, and as such is ready for addition to lubricating oil without further purification.

We prefer to employ as starting materials anti-oxidants, prepared as set forth above and in the aforesaid co-pending applications, and having suitable mechanical til physical properties within the following range:

Gravity, API 15.0 to 25.0 Specific gravity. 60/

60 F 0.9659 to 0.9042 Viscosity, SUV at I F., sec 150 to (solid) Color Water white to 7 (NPA) Pour point, (liquids only), F 0 to 30 Melting oint, (solids only), "F 80 to 225 Our invention, in its broadest aspects, however, is not limited to the preferred starting material mentioned hereinabove but contemplates the manufacture of inhibitors of the general class described from any alkylated phenols so long as such alkylated phenols possess definite antioxidant properties, are insoluble in water, insoluble or only slightly soluble in dilute alkali, and are permanently soluble up to 5 per cent in paraflin oils. For example, we may employ as starting materials anti-oxidants prepared by reacting various light cracked hydrocarbon distillates and other normally liquid olefinic hydrocarbon mixtures, with phenol in the presence of sulfuric acid, as described in the aforesaid copending applications. It is a requisite of such olefin-phenol reaction products, however, insofar as the present process is concerned, that one or more secondary and/or tertiary carbon linkages be present in the compound.

The anti-oxidant value of this starting material should be such that the addition of 0.01 per cent by weight thereof to standard asoline stock having an oxygen stability test (E. G. C. method) of, say, minutes, will raise the oxygen stability to at least 240 minutes. Less potent antioxidants are'unsuitable as starting materials.

The character of the final phosphorus-containing inhibitor will of course vary with the character 'of the phenolic and olefinic material employed in the manufacture of the anti-oxidant starting material, with the extent of the absorption of the olefin, and with the amount of phosphorus subsequently introduced. All of these factors are however very intimately interrelated. These are the primary factors, but it will be obvious that there are numerous secondary factors, for example the degree of purification and decolorization of the anti-oxidant starting material.

Naturally, it is to be expected that the viscosities, specific gravities and other physical characteristics of the particular phenols employed have a corresponding eilect upon the product, to some extent at least; this effect may, however not always, hold true where the degree of olefin absorption varies over comparatively wide limits and where the percentage of phosphorus in the final compound also varies.

When cresylic acid, ortho-cresol and metacresol and the like are used in the manufacture of the antioxidant, we prefer to limit the olefin absorption to around one mol per mol of the phenolic material, 1. e. to give a water-insoluble product representing roughly to per cent by volume of the original phenol, in order ultimately to secure inhibitors that are sufliciently soluble in the higher gravity oils; the result of carrying the absorption of olefin farther is to make the anti-oxidant product less capable of absorbing the desired amount of phosphorus in the final stage.

When the anti-oxidant starting material is prepared from phenol (CsHaOH) itself, e. g. "90

if the degree of absorption of the olefin in the phenol is carried farther, for example to three mols of olefin per mol of phenol, the resultant compound may be capable of absorbing up to three or four per cent of phosphorus, but containing this much phosphorus the final inhibitor product will tend to be a solid and to be insufllciently soluble in highly parafilnic oil; additions of one per cent may give the oil a hazy or cloudy appearance.

The preferred olefins are those containing from three to eight carbon atoms per molecule; the higher the molecular weight of the olefin, the more viscous the final phosphorus-containing product will be. Olefins containing more than eight carbon atoms per molecule tend to reduce the phosphorus content of the final inhibitor product. Ethylene (Cal-I4), on the other hand, is insufliciently reactive, requiring the use of fuming sulfuric acid and does not sufilciently reduce the acidity of the original phenol.

The best olefin starting materials are those containing from three to five carbon atoms per molecule, especially butylenes; fractions obtained from gases produced in the pyrolysis of hydrocarbon oils and rich in olefins of this approximate range represent advantageous and available raw materials.

After the reaction between, the phenol and olefin has been carried to the desired degree of completion, the product is' washed with water and dilute caustic soda in the manner set forth hereinabove and in the aforesaid co-pendlng applications. The resultant water-insoluble antioxidant material is then preferably dried. The drying may be accomplished by filtering this material through adsorbent clay or the like, the effect of which is to dehydrate and decolorize. Or, the drying may be accomplished by heating the anti-oxidant material to about 400 F. in suitable apparatus; this procedure dehydrates and tends to darken the anti-oxidant material.

The dry anti-oxidant may then be treated directly with phosphorus trichloride, or it may first be distilled to separate undesirable lowboiling and high-boiling constituents, respectively. Thus we may distill under a vacuum of from -11 in. to 28 in. Hg, to recover a fraction distilling over between 400 and 550 R, which fraction may then be treated with phosphorus trichloride. The lower boiling material, and sometimes also the residue, may be recycled for further reaction with olefines in the presence of sulfuric acid, or used as an anti-oxidant.

Where the anti-oxidant material has been prepared from olefins containing primarily three or four carbon atoms per molecule, the phosphorus trichloride employed for the preparation of the final product should be such as to give a product containing not more than about 5 per cent, and preferably from 3.5 to 4.0 per cent, of phosphorus. Any substantial increase in the phosphorus 'content above about 5 per cent tends to reduce the solubilit of the product in hydrocarbon oil, to make the product too active at ordinary temperatures, and also tends to make it difficult to dechlorinate the product. On the other hand there is no absolute lower limit to the phosphorus con tent; this is primarily a matter of the desired pared from oleflns containing five or more carbon atoms per molecule, it is better to use only so much phosphorus trichloride as will give a final inhibitor product containing not more than about 3 per cent of phosphorus, the preferred range being from 1.7 to 3.0 per cent. With this type of olefinic material any attempt to raise the phosphorus content of the ultimate product above about 3 per cent tends to result in a product which is too viscous for practical purposes.

Working with anti-oxidants prepared as described in the aforesaid application, Serial No. 99,488, we have found that the amount of phosphorus trichloride required ranges from 5 to per cent by weight of the anti-oxidant, under practical working conditions.

The following examples will serve to illustrate our process in some of its more specific embodiments- EXAMPLE I (11) Preparation of anti-oxidant starting material 50 gal. of 90 per cent phenol were mixed with 20 lb. of 98 per cent "black acid, the latter being a recovered acid obtained from acid sludge produced in washing hydrocarbon oil with sulfuric acid. The per cent phenol employed had the following properties:

Specific gravity, 60/60 F 1.050 Melting point, capillary tube, "F 91.9 Color, NPA 5 The phenol was placed in a suitable iron vessel and heated to a temperature of F. olefinic gas was then introduced slowly to agitate. the phenol and the acid was added in two batches, 10 lb. at first and the remaining 10 lb. two hours later. The temperature at the end of two hours was F. and the mixture was maintained at this temperature for 16 hours, olefinic gas being passed through the mixture during this time at the rate of 1600 cu. ft. per hour. The operation was conducted under a pressure of from 15 to 25 lb. per sq. in.

The olefinic gas employed in this example was a cracked hydrocarbon gas fraction obtained in the pyrolysis of hydrocarbon oil, and having a specific gravity of 1.785. Upon agitation of a sample of this gas with 64 per cent sulfuric acid, the acid absorbed 12.5 per cent by volume of the gas, which may be considered as isobutylene and dienes. The remainder of the sample lost 20 per cent by volume (based on the original volume of gas) by absorption in 8'7 per cent acid, which may be considered as propylenes, butylenes and similar constituents. The remainder of the sample, upon being washed with bromine water, following the two acid washes, lost 2.6 per cent by volume (based on the original volume of gas), which may be considered as ethylene. The gas, therefore, contained 34.1 per cent by volume of unsaturated constituents.

Upon completion of the operation, there was produced a material representing 300 per cent by volume of the original phenol, i. e. 150 gallons.

The crude product was then raised from 200 to 212 F., and 20 gal. of 10 per cent caustic soda solution were added to neutralize the sulfuric acid present. The resultant product, after removal of the caustic layer, was washed with boiling water, live steam being introduced during the washing operation, and was then allowed to settie for two hours after which the aqueous layer was withdrawn. The remaining material was Gravity, API 21.6

Viscosity, SUV at 100 F., seconds 122 Color, NPA. Dark Pour point, "F (b) Preparation of final inhibitor 82.5 parts by weight oi the foregoing antioxidant material were first heated to 400 F, to

insure removal of the last traces of moisture.

It was then cooled to 80 F., and at this point the mixture was stirred and 17.5 parts by weight of phosphorus trichloride were added through a spider at the bottom of the vessel, the rate of addition being controlled so as to add not more than 8 parts of phosphorus trichloride per hour. During the addition of the phosphorus trichloride, the mixture was vigorously stirred by mechanical means and the temperature was maintained below 120 F. until all of the phosphorus trichloride had been added. After all the phosphorus trichloride had been added, the temperature of the reaction mixture was gradually brought to between 350 and 380 F. (Usually this heating is accomplished within a period of four to eight hours.) This heat treatment reduced the chlorin content of the product to about 0.2 per cent. The reaction product was then cooled and withdrawn from the vessel, giving a product having the following properties:

Gravity, API 8.7 Viscosity, SUV at 210 F., sec 93 Color, NPA 4.75 dilute Pour point, "F 50 Phosphorus, per cent by weight 3. 96 Chlorine. per cent by weight 0. 19

EXAMPLE II (a) Preparation of anti-oxidant starting material 20 gal, of "90 per cent phenol were mixed with 5 per cent by weight of 94.5 per cent sulr furic acid (C. P.), the phenol being the same as that employed in Example I. Olefin gas, composed primarily of C4 hydrocarbons, was then introduced into close contact with the phenol-acid mixture until the volume of the reacting mixture increased to about gal. This product was washed with 10 gal. of 10 per cent caustic soda and later with 10 gal. of water. After washing, the recovered product, amounting to about 40 gal., was then distilled under a moderate vacuum. The distillate was cut into three fractions. That fraction distilling over at vapor temperatures between 400" and 550 F. amounted to about per cent of the original 40-gallon charge and had the following properties:

Gravity, "API 1 18. 6 Viscosity, SUV, seconds:

F 211 210 F 36.4 Pour point, F 5 Color, NPA 2. 0 Neutralization No 1. 64

(b) Preparation of final inhibitor 82.5 parts by weight of the above product were treated with 17.5 parts by weight of phosphorus trichloride. The resulting material had the following properties:

(a) Preparation of anti-oxidant starting material 1153 parts by weight ofmeta-cresol (C. P.) were mixed with 32 parts by weight of 94.5 per cent .sulfuric'acid (C. P.) Olefin gas, similar to that employed in Example I, was thenintroduced into close contact with the phenol-acid mixture until the weight of the reacting mixture was 178.5% of the original cresol. This product was washed with 10% by volume of 10 per cent caustic soda and later with a similar quantity of water. After washing, the recovered product, amounting to about by weight of the original cresol. was then distilled under a moderate vacuum. The distillate was out into three fractions. That fraction distilling over at vapor temperatures between 400 and 550 F., amounted to about 81.2 per cent of the original charge to the still and had the following properties: Gravity, API 12.5

(b) Preparation of final inhibitor 82.5 parts by weight of the above distillate were treated with'17.5 parts by weight of phosphorus trichloride and the resulting material had the following properties:

Gravity, API 5.3 Viscosity, SUV at 100 F., seconds 609 Phosphorus, per cent by weight 4. 12

EXAMPLE IV (a) Preparation of anti-oxidant starting material 20 gal. of 90 per cent phenol" were mixed with 5 per cent by weight of 94.5 per cent sulfuric acid (C. P.), the phenol being the same as that employed in Example I. Olefin gas, composed primarily of C4 hydrocarbons, was then introduced into close contact with the phenolacid mixture until the volume of the reacting mixture increased to about 45 gal. This product was washed with 10 gal. of 10 per cent caustic soda and later with 10 gal. of water. After washing, the recovered product, amounting to about 40 gal., was then distilled under a vacuum of 11 to 12 inches of mercury. The distillate was cut into three fractions. That fraction distilling over at vapor temperatures between 300 and 550 F. had the following properties:

Gravity, AP 16.8

Viscosity at 100 F., seconds Color, Saybolt 13 (b) Preparation of flnal inhibitor 82.5 parts by weight of the above distillate were treated with 17.5 parts by weight of phosphorus trichloride and the resulting material had the following properties:

Chlorine, per cent'by weight 0.06

. oils, and when added thereto in amounts up to one or two per cent by weight, result in improved and advantageous lubricating compositions.

These inhibitors are all permanently soluble in hydrocarbon oils, even in highly paraffinic oils, and they strongly inhibit corrosion of metal bearing alloys, such as those of silver, cadmium and copper, under conditions where the oil alone would cause such corrosion. On the other hand, these inhibitors are stable at ordinary temperatures and do not tend to settle out or form sludge, or to deposit on or attack metal surfaces such as those of tin plate, terne plate and the like, when packaged and stored prior to sale and use.

Not only do these have excellent anti-oxidant properties, but their chemlcal'nature is such that should any hydrolysis occur, the organic products of such hydrolysis are in themselves anti-oxidant materials; in these respects our product differs sharply from simple aryl esters of phosphorous acid, such as triphenyl phosphite, which is far more subject to hydrolysis and which upon hydrolysis yields highly corrosive phenol.

It will be clear from the description given hereinabove that the phosphorus content of the final inhibitor product is important from two aspects: it influences the solubility of the product in paraffin oils and it also influences the effectiveness and reactivity of the product. Too high a phosphorus content tends to cause the inhibitor to deposit out on metal surfaces at temperatures considerably below bearing operating temperatures. It will be obvious that to closely regulate the phosphorus content and to produce a wide range of materials varying but slightly from each other in phosphorus content and solubility are important desiderata; it is one of the advantages of our invention that we are able to accomplish such regulation and variation.

Such flexibility is diflicult or unsatisfactory with respect to simple aryl phosphites, such as triphenyl phosphite and analogous compounds,

and also with respect to some alkylated phenols having normal alkylation linkages. For example, if dirnethyl phenol is treated with phosphorus trichloride to such extent 'as to absorb the theoretical amount of phosphorus, as phosphite, the resultant product is insufiiciently soluble in highly paraffinic oils, and tends to deposit out on metal containers at ordinary temperatures, or if the concentration of phosphorus is limited to a point Where the product is soluble in highly paraffinic oils to the desired extent, the inhibiting and anti-oxidant values of the product are unsatisfactory.

In our process the phosphorus content of the product, the distillation and. fractionation of the intermediate anti-oxidant product having an especial influence upon these characteristics of the inhibitor.

We, therefore, regulate these various factors with reference to each other, and with regard to the starting materials available, in order to secure inhibitors of desired temperature-responslveness,

"activity, solubility, viscosity and color, within inhibitor may be varied by adjusting any one or more of the following factors: (1) the character and molecular weight of the phenolic starting and fractionation as may be employed. All of the above factors also exert a definite influence upon the color and viscosity of the final inhibitor limits corresponding to the use to which the flnal inhibitor is to be subjected.

Wherever the expression highly paraflinic oil is employed herein and in the claims hereinafter made it is in general intended to indicate lubricating oils conforming in physical properties to oils prepared from Pennsylvania crudes; these.

highly parafilnic oils are either oils derived from Pennsylvania crudes or oils which have been refined or blended to approach or even exceed the latter oils 'in parafflnicity. Where various materials are referred to as being soluble in such paraffinic oils, this expression is intended to mean that such materials may be incorporated into such oils in amounts up to ten per cent, without producing any haziness nor cloudiness in the appearance of the resultant compositions, at least under atmospheric temperatures and-under the ordinary conditions to which such oil comositions are subjected in storage and handling prior to their actual use as lubricants.

A further advantage of our process and product is that the principal ingredients employed in the manufacture of the final product, namely olefins, are cheap and available to the refiner.

The following tables will serve to illustrate the effectiveness of our inhibitors and the value of lubricating compositions containing them:

TABLE I i i or pre- Untreatcd oil pared as in Example 1) Makeup, percent by weight:

Lubricating oil 10 100 09. l Inhibitor .L- 0.9

General properties:

Gravity, API 32. 5 32. 3 Specific gravity, /60 F 0. 8628 0. 8630 Viscosity. S V- F.-. 183.6 185 F 100.2 I 219 46. 0 46. 3 Viscosity llldGIL 107 107 V G constant 0. 804 0. 800 Flash, 00 410 400 Fire, 0C: 13 470 470 Pour point, F 0 0 Color, NPA 1.5 1.75 Chlorine, percent Trace Phosphorus. percent..- 0.036 Neutralization No Nil 0. 04

Oxidation test:

' 0.1% sludge formed in, hr- 27 52 1.0% sludge formed in, lir. 148 184 Oxidized oil- Time oxidized. hr 100 100 Gravity, API 30. 9 8 32. 2 31. 6 Viscosity. SUV- 100 F 234 f 267 199 219 54. 1 '51. 2 47. 3 4B. 5

17. 3 14. l 2. 1 Viscosity index." 103 10; 1( Carbon residue, percent. 0. 49 0. 80 0. l0 0. 48 Slud e, percent 0. 25 0. 50 0. 09 0. 33 N eutralizatlon No 2. 20 3. 20 0. 42 l. 52

Sptrcial oxidation and corrosion 'Time oxidized, hr 45 48 Oil bath temperature, F 347 '347 Air rate: cc. per hr 2000 2000 Oil volume: cc 300 300 Cadmium-nickel bcaring We ght before test, g 37. 1883 30. 5445 Weight. alter test,,g 36.4031 v36. 5292 Change in weight, g. 0. 0052 0. 0153 Weight loss percent 1.87 0. 041 Appearance E tehed Good By way of comparison with the above, the following Tables IV and V list results obtained by adding triphenyl phosphite to an oil similar to the oil used in the tests listed in Tables I to III. The superior value of our inhibitors will be obvious.

Tiis'u II TABLI IV Oil containing Untreated oil tripheliliiyl Untreated oil Make-u rcent b 1101.: in MF 1%) Lube-lig ting 011-? 100 00. .1 Trrlifhenyl phosphite Gene properties:

Make-up, perce t by Weight: Gravity, API 33.0 32 6 Lubri atlng o Specific gravity: 00700 F 0. 3002 0. 0021 Inhibitor 0 Viscosity suv- General roperties: 100 F 132 113 Grav ty, API 3'2. 5 32.3 99 97 Sgeciflc gravity, 00/0o F. 0.3023 0. 3030 m 5 a D 1, ,Igfll.,60 F 1- H93 112 110 Viscosity SU 0. 300 0. s03

100 i 110 184 420 415 10 F 40 40 490 4115 Viscosity index. 103 105 0 0 V- constant... 0.804 0.806 1.25 l. Flash, 00:91 415 400 0.01 0.05 Fire, 00: M 475 Nil 0. i0 Pour p0int.F 0 0 Clear Hazy Color, NPA... 5 5 Normal Phenolic Carbon residue, percent- 0. Q2 0. 0B 0 1110 11i'e liz l i ion N0 N11 Journi il speeda R. P. M 000 600 x at on as Rubb s it. r n 40 40 0.0 percent sludge formed, 40 Lever fi id jlglnngun 14 10 1.0 percent sludge formed, hr. 190 200 Torque, m n x 22 24 0 d n gngflloadt, Eli/sq. 112.. a 7000 8000 X1 [Z8 0 8811 m are,

Time oxidized, hr 50 100 50 100 fffi 83 80 gmvitiyt, Ha l 304! 323 25 Final 100 135 myr S al oxidation and corrosion test:

100 F 2% 244 194 'iime niddined, hr 43 4s 210 49 49 47 011 bath temperature, F 341 341 Viscosity at 100 F.- Air rate, cc. per hr N00 N00 Increase, percent. 26. 3 36. 3 5. 4 ll. 4 oxidized on 300 v 300 giscggity 1 1111 2; 0 :8 g: Gravity, "API.-. 31.0 32.3

n esi ue at r Flaky Flaky Flaky Flaky fgg ji SUV moondk 288 194 1.04 2.03 0.54 1.04 49 46 5 0. 21 0. 41 0. l0 0 m6 0.40 0. 21 1. 20 1.0 Sludge. roent Nil 0. l7 i l t ig ht n sheik 36 3130 30 1543 6 ore TABLE III Weight amitest.-. 35. mo 30. 1787 Weight change, 5 0. 4289 +0. 0239 Weight change, percent... 1. 18 Nil Appearance... Badly etched Good 011 with inhib- Untreated ltor mpared 40 Team: V

oil as in xample III) Oil containing M k n, j M Untreated oil tlgphellllyl a o-u percen y W0 E I 05 ite Lub ricating 011 100 00. 4 P P G lngilibitonii. 0. 6 b h ener prope ies: Make-up, roent y weig t:

Gravity; Ari 5 2 Lubrii ting oil 10 100 09. 1 Specific gravity, F 8523 Triphenyl phosphite 0.9 Viscosity, SUV- Oxidation test:

100 F 136 186 0.1% sludge formed in, hr. 27 48 210 F.- 1.07 sludge mined in, hl' 148 185 Viscosity index.. 104 102 constant 0. 804 306 50 Oxidized oil-.- Flash, 00: F.. 405 Time, oxidized, hr 50 100 50 100 Fire, 00: F..- 465 475 Gravity, "111 1 30. 0 30.8 32.2 31.1 Pour point, F 0 0 Viscosity, SUV 0010:, NP A 100 F 233 266 130 213 Carbon residue, pe 210 F 40 51 40 41 Neutralizati n N 1111 Vise. at 210 F., increase:

Special oxidation and percent 0. 4 11.3 1. s 4. 3 Time oxidized, hr. 48 48 55 Viscosity index 106 100 101 105 011 hath temperat 341 Carbon residue, percent. 0. 43 0. s0 0. 1s 0. 44 1111- rate: 00. per inm m Sludge, percent 0. 24 0. 40 0. 13 0. 31 011 volume: c- 300 Neutralization No 2. 20 3. 2 0. 30 1. 111 Oxidized oil:

Gravity, API 31. 2 32. 2 210 191 In comparing the results given in Tables I111. 210 F. 0 g 0 f3 and III with those given in Tables IV and V, it gag i-fffff f" ojm will be observed that our inhibitors are much Neutralization .83 58 more efl'ective than triphenyl phosphite, on a. aggfi'ffig g fgj 3mm 3mm basis 01 equal phosphorus content in the treated Weight rmtest, 11.. 86. 5 fi- 3??? oil; whereas our inhibitors contain from one to 3mg: 335%: 5 25 2; +6 five per cent of phosphorus, triphenyl .phosphite Bearing appearance Etc ed 000d contains approximately ten per cent of phosphorus. This is important because phosphorus is by far the most costly constituent of these materials.

minum chloride.

In the "Oxidation test" referred to in Tables I, II, and V, 300 cc.-samples of oil are maintained at a temperature of 341 F.,

' ing shell.

-and air, at the rate of 2000 cc. per hour, is

bubbled through the oil in contact with the bear- At the end of 48 and 96 hours, the

access? In these tests, a good grade of motor oil, without inhibitor, caused bearing failures after having been run for the equivalent or from one thousand to two thousand miles, at speeds around fiity miles per hour, and under loads oi around fiity brake horse power. The same oil when protected by the addition 01' from 0.5 to 1.0 per cent by weight of our improved inhibitor, gave no evidence 01' serious attack on the bearings loss of weight and the condition of the bearing bearing metal. In this way, the actual bearing face is subjected to severe deteriorative conditions. By comparison of the results of such tests with actual service tests, we have found them to be in substantial agreement as to the suitability of particular lubricants.

In so testing our lubricants, we have employed,

These shells comprise.- a suitable metal backing faced with the alloy after being driven under the same conditions for the equivalent of around five thousand miles. After these tests with our improved lubricating compositions, the appearance of the bearings in all cases was good and the weight loss of the bearings was only such as would normally be expected, assuming the entire absence oi corrosion. I Our improved lubricating compositions, in these tests, showed results fully comparable with those obtained by the use of lubricating oil containing triphenyl phosphite as an inhibitor; however, the other disadvantages inherent in the use or triphenyl phosphite. and referred to hereinabove are avoided by the use of the inhibitgrs prepared as set forth hereinabove.

Moreover, comparative motor tests made on oils containing our inhibitors and uninhibited oils, respectively, showed that the use of our inhibitors resulted in a marked improvement in among other, bearings oi the following approximate composition:

Metal Percent Cadmium. Silver Copper the character of the used oil at the end of the motor tests, aside from difierences determinable by test alone, the appearance of the oil is greatly improved; this is obviously of importance from the sales standpoint.

Various modifications in the operating procedures mentioned hereinabove will suggest themselves to those skilled in the art. For example, we have described washing the phenol olefin reaction product with water and dilute caustic soda solution to effect neutralization and removal of the acid or acids (e. g. sulfuric acid and sulionic acids) remaining in the rebearing shells used have an alloy facing of only 0.008 to 0.012 in. thickness on a highly resistant backing and the observed losses in the reported tests often represent a loss of the order of ten per cent of the alloy facing.

By way of illustrating the value of our inhibitors in imparting extreme-pressure characteristics to oils, the results given in the following Table VI are interesting; these results were obtained by means of the well-known Almen test, which does not require description here.

The inhibitor here used was one containing 4.07 per cent of phosphorus, prepared in accordance with the procedure shown in Example I. The treated oil, giving the improved results noted, contained 0.6 per cent by weight 01' the inhibitor.

In order to demonstrate the eilectiveness of our improved inhibitors, we have carried out actual motor tests on a standard automobile engine equipped, for the purposes of these tests,

iii

with cadmium-silver and copper-lead bearings.

action mixture after the introduction of the olefins has been discontinued. Such neutralization and removal may be effected in other ways, as by extraction with aqueous alcohol, contact with solid alkalis such as calcium or sodium carbonate, or by contacting the reaction mixture with solid adsorbents such as fullers earth, activated carbon, or the like.

While we have described our invention hereinabove with reference to various preferred forms and embodiments, and with reference to various specific examples, it will be understood that our, invention isnot limited to the details of such illustrative embodiments or examples but may be variously practiced and embodied within the scope oi! the claims hereinafter made. Moreover, while we have in certain instances specifically given certain preferred ranges and proportions, it will be understood that our invention is not limited thereto and that such'preferred ranges and proportions are in general related for particular products and particular purposes; variations in proportions and in the methods of preparation result in products of different characteristics, such products having individual advantages and 'utilities.

What we claim is:

1. The method of preparing an oil-soluble organic phosphorus compound suitable as an improvement agent for hydrocarbon oils, which comprises reacting an olefin and a phenol in the presence of sulfuric acid, and treating at least a portion 01' the resultant product with phosphorus trichloride to obtain a final inhibitor product containing from about one to five per cent of phosphorus.

2. The method of preparing an oil-soluble organic phosphorus compound suitable as an improvement agent for hydrocarbon oils, which comprises reacting phosphorus trichloride with 3. The method of preparing an oil-soluble.

organic phosphorus compound-suitable as an improvement agent for hydrocarbon oils, which comprises passing a gaseous olefin into contact with a phenol in the presence of sulfuric acid until the reacting mixture has increased in volume from 3 to 250 per cent on the original phenol, washing the resultant anti-oxidant product with water and dilute alkali, and reacting at least a portion of the washed anti-oxidant productwith phosphorus trichloride to obtain a final oil-soluble material containing not more than about five per cent of phosphorus.

4. The method of preparing an oil-soluble organic phosphorus compound suitable as an improvement agent for hydrocarbon oils, which comprises passing a gaseous olefin into contact with a phenol in the presence of sulfuric acid until the phenol-acid mixture has absorbed from one to three mols of olefinper molof phenol,

washing the resultant anti-oxidant product with water anddilute alkali, and reacting at least. a portion of the washed anti-oxidant product with from five to thirty per cent by weight of phosphorus trichloride.

5. An improvement agent for hydro-carbon lubricating oils comprising a phosphorus-derivative of a compound selected from the class consisting of water-insoluble secondary and tertiary alkylated phenols. I

6. An improvement agent for hydrocarbon lubricating oils comprising a phosphorus-derivative of a compound selected from the class consisting of water-insoluble secondary and tertiary alkylated phenols, said agent containing not more than about five per cent of phosphorus.

7. An improvement agent for hydrocarbon lubricating oils comprising a phosphite ester of a water-insoluble olefin-phenol reaction product.

8. A lubricant comprising a hydrocarbon oil and a small quantity of a phosphorus derivative of a compound selected from the class consisting of water-insoluble secondary and tertiary allqlated phenols, said derivative containing not more than 5 per cent of phosphorus.

9. A method of lubricating bearing surfaces which comprises maintaining between bearing surfaces, one of which is analloy from the class consisting of binary and ternary alloys of cadmium, silver, nickel, copper and lead, a film of lubricating oil which initially produces an effectlve lubricating action but which would normally'tend to corrode the aforesaid alloy, and

maintaining the eiiectiveness of the lubricating oil by incorporating therein a phosphorus-derivative of a compound selected from the class ,7 consisting of water-insoluble secondary and tertiary alkylated phenols in small but sufilcient V proportion substantially to reduce the corrosion.

10. The method of preparing oil-soluble organic compounds suitable as improvement agents for highly paraifinic lubricating oils which comprises reacting an olefin and a phenol in the presence-of sulfuric acid washing the resultant product with water and dilute alkali; treating at least a portion of the product with phosphorus trichloride, and regulating the degree of absorption of olefin in the initial reaction stage with reference to the specific chemical character of the phenol and olefin, to secure an intermediate water-insoluble product which, when treated in the subsequent reaction stage with phosphorus trichloride in the required amount to introduce from one to five per cent of phosphorus into the aforesaid intermediate product, will yield a phosphorus-containing product soluble in highly 'parafiinic 011.

11. A motor oil normally tending-to produce corrosion of the bearing metals of the class com-' prising primary and ternaryalloys. of cadmium,

silver, nickel, copper and lead, under conditions of automotive use,having added thereto a small proportion, not more than two per cent of a phosphorus-derivative of a compound selected from the class consisting of water-insoluble secondary and tertiary alkylated phenols. eifective substantially to retard corrosion, said derivative containing not more than 5 per cent of phosphorus.

12. The method of preparing oil-soluble orgarlic compounds suitable as improvement agents for highly paraflinic lubricating oils, which comprises reacting an olefin and a phenol in the presence of sulfuric acid, washing the resultant product with water and dilutealkali, treating at least a portion of the product with phos- TROY LEE CAN'TRELL. JAMES o'rno TURNER. 

